The present disclosure relates to the technical field of chemical synthesis, particularly to a functionalized polymer containing a carboxyl group, a preparation method thereof, and an application thereof in preparing a supported metal catalyst, a supported metal catalyst, and a preparation method of a penem antibiotic intermediate by a carbene insertion reaction catalyzed by a supported metal catalyst.
Since a concept of applying a light divinylbenzene cross-linked chloromethylated polystyrene resin in solid phase peptides synthesis reported by Merrifield for the first time almost half a century ago, it has become more and more common to apply polymers in synthesis and purification of the compounds using different methods. Recently, various macromolecule materials, such as JandaJel and Tentageld have been developed. These materials have been not only applied as carriers of solid phase synthesis, but also used for supported reagents, catalysts and so on. An advantage of these materials over the Merrifield resin is: a reaction center is on a terminal of a polyether chain, which is away from a non-polar polystyrene framework in a resin. Therefore, demands for polymer swelling are somewhat reduced.
Generally, a chiral or achiral ligand (such as a phosphorus ligand and an amino ligand) is connected on a polymer by means of a covalent bond or a non-covalent bond, which is aimed to support a heavy metal catalyst. The polymer is used as a carrier to support the heavy metal catalyst by coordination of the heavy metal catalyst and the ligand on the carrier. The aspect has been widely reported (Chem. Rev. 2009, 109, 815), and a formed supported catalyst is able to catalyze a specific reaction, which will be illustrated with an example as follows:
A ketone ester compound shown in the following formula (VI) is prepared by a diazo compound shown in formula (V) under the catalysis of a catalyst 1 (a rhodium catalyst).

The structural formula of the catalyst 1 is as follows:

wherein R2 is a protecting group of carboxyl, R3 is hydrogen or methyl, X is an oxygen atom or a nitrogen atom substituted by an alkyl group, and R4 is an alkyl radical substituted appropriately.
Specifically, the diketone ester compound shown in the foregoing formula (VI) is prepared by the diazo compound shown in formula (V) through an N—H insertion reaction. The reaction applies a rhodium catalyst compound shown above as a catalyst. The rhodium catalyst compound is able to form a rhodium carbene with the compound shown in the formula (V), which can release a diazo radical at the same time to form a product (VI) eventually. The product is an important penem antibiotic intermediate.
However, a supported metal catalyst prepared using the polymer having the phosphorus ligand and the amino ligand and so on as a catalyst carrier has the following disadvantages: (1) poor chemical properties to result in easy loss of the catalyst, and a high loss rate of an expensive heavy metal supported thereon; (2) low yield of preparation of the catalyst; (3) generally low catalytic activity of the catalyst. The catalytic activity, mechanical properties and so on of the catalyst have a direct impact on the cost of industrial production especially when the expensive heavy metals supported in the catalyst comprising rhodium and so on.